Light sensing device with outgassing hole in a light shielding layer and an anti-reflection film

Abstract

A light sensing device includes a substrate, a light sensing area on the substrate, and a light shielding layer over the substrate. The light shielding layer does not cover the light sensing area. At least one outgassing hole is formed through the light shielding layer.

What is claimed is: 
     
       1. A light sensing device, comprising:
 a substrate; 
 a light sensing area on the substrate; 
 an anti-reflective coating film over the substrate; 
 a light shielding layer over the anti-reflective coating film, the light shielding layer not covering the light sensing area, the light shielding layer comprising a conductive material; and 
 at least one outgassing hole formed through the light shielding layer, the at least one outgassing hole completely extending through the light shielding layer, the at least one outgassing hole at least partially extending through the anti-reflective coating film, portions of the conductive material exposed by all sidewalls of the at least one outgassing hole forming a single continuous region of the conductive material, an entire area of the substrate enclosed by a perimeter of the least one outgassing hole being free from the conductive material, the at least one outgassing hole being configured to release gasses and moisture absorbed in the anti-reflective coating film. 
 
     
     
       2. The light sensing device of  claim 1 , wherein the anti-reflective coating film comprises high-k dielectric material. 
     
     
       3. The light sensing device of  claim 1 , wherein the anti-reflective coating film comprises multiple layers. 
     
     
       4. The light sensing device of  claim 1 , wherein the light shielding layer comprises copper, aluminum, or tungsten. 
     
     
       5. The light sensing device of  claim 1 , wherein the at least one outgassing hole has a width or a diameter of at least 1 μm. 
     
     
       6. The light sensing device of  claim 1 , wherein the at least one outgassing hole is at least 1 μm away from an edge of the light shielding layer. 
     
     
       7. The light sensing device of  claim 1 , wherein the light shielding layer has a width of at least 10 μm. 
     
     
       8. The light sensing device of  claim 1 , wherein the at least one outgassing hole has a linear, rectangular, square, circle, or oval shape. 
     
     
       9. The light sensing device of  claim 1 , wherein four outgassing holes having a linear shape surrounding on four sides the light sensing area that has a rectangular shape. 
     
     
       10. The light sensing device of  claim 1 , wherein multiple circular outgassing holes are distributed in a linear pattern along the light shielding layer with uniform spacing in between. 
     
     
       11. A method of fabricating a light sensing device:
 forming an anti-reflective coating film over a substrate having a light sensing area; 
 forming a light shielding layer over the anti-reflective coating film, wherein the light shielding layer does not cover the light sensing area, the light shielding layer comprising a conductive material; and 
 patterning the light shielding layer to form at least one outgassing hole through the light shielding layer and at least partially through the anti-reflective coating film, a single continuous portion of the conductive material extending along all sidewalls of the at least one outgassing hole, an entire area of the substrate enclosed by a perimeter of the least one outgassing hole being free from the conductive material, the at least one outgassing hole being configured to release gasses and moisture absorbed in the anti-reflective coating film. 
 
     
     
       12. The method of  claim 11 , wherein the at least one outgassing hole is formed at least partially through the anti-reflective coating film. 
     
     
       13. The method of  claim 11 , wherein the anti-reflective coating film comprises high-k dielectric material. 
     
     
       14. The method of  claim 11 , wherein the anti-reflective coating film comprises multiple layers. 
     
     
       15. The method of  claim 11 , further comprising thinning the substrate. 
     
     
       16. The method of  claim 11 , wherein the light shielding layer comprises copper, aluminum, or tungsten. 
     
     
       17. The method of  claim 11 , wherein the at least one outgassing hole is formed at least 1 μm away from an edge of the light shielding layer, the at least one outgassing hole has a width or a diameter of at least 1 μm, and the light shielding layer has a width that is at least 10 μm. 
     
     
       18. A light sensing device, comprising:
 a substrate; 
 a light sensing area on the substrate; 
 an anti-reflective coating film over the substrate; 
 a light shielding layer over the anti-reflective coating film, the light shielding layer not covering the light sensing area; and 
 at least one outgassing hole formed through the light shielding layer, the at least one outgassing hole extending below a bottommost surface of the light shielding layer and at least partially extending through the anti-reflective coating film, the at least one outgassing hole being configured to release unwanted gasses and moisture absorbed in the anti-reflective coating film, wherein the at least one outgassing hole is at least 1 μm away from an edge of the light shielding layer. 
 
     
     
       19. The light sensing device of  claim 18 , wherein the at least one outgassing hole comprises a plurality of outgassing holes, wherein the plurality of outgassing holes forms a perimeter around the light sensing area. 
     
     
       20. The light sensing device of  claim 18 , wherein the anti-reflective coating film comprises multiple layers.